Flask geometry
S. pristinaespiralis cultures were performed in unbaffled shake flasks provided
by Schott (Clichy, France). The dimensions of the flasks used for the cultures are
summarized in Fig. 1. Preliminary cultures in three- and four-baffles flasks did not
allow the establishment of a relationship between power dissipation or kLa and the
production of pristinamycins. This might be due to the attachment of most of the
biomass on the surface of flasks during cultures at high agitation rates as reported
by Galindo et al. [23]. Another possible explanation might be little changes in baffles
design, medium splashing on the flask wall and on the cotton plug, more complex
hydrodynamics and more difficult quantification of mechanical power dissipation
and oxygen transfer as explained by Büchs [18]. The baffled systems have thus not
been considered in the present study.